The present invention relates to a motor-driven compressor.
A motor-driven compressor includes a metal housing accommodating a compression unit, which compresses and discharges refrigerant, and an electric motor, which drives the compression unit. A cover that defines an accommodation chamber is coupled to the housing. The accommodation chamber accommodates a motor driving circuit that drives the electric motor.
When the cover is made of metal, the overall weight of the motor-driven compressor increases. The use of a resin cover allows the motor-driven compressor to be lighter. However, a resin cover would transmit electromagnetic noise from outside the compressor to the motor driving circuit. In addition, electromagnetic noise from the motor driving circuit may leak out of the compressor through the resin cover.
Accordingly, Japanese Laid-Open Patent Publication No. 2008-215236 discloses an insulating layer (resin cover), which is made of an insulating material such as resin and rubber, and a conductive layer (shield), which is made of a conductive material such as aluminum and iron. The insulating layer and the conductive layer, which are layered and fixed to each other, are coupled to a housing by a bolt, with the conductive layer in contact with the housing. Electromagnetic noise from the exterior is blocked by the conductive layer and transmitted to the housing. This suppresses electromagnetic noise entering the accommodation chamber through the insulating layer. In addition, electromagnetic noise from the motor driving circuit is blocked by the conductive layer and transmitted to the housing. This suppresses the leakage of electromagnetic noise from the motor driving circuit to the exterior through the insulating layer.
However, the sealing between the conductive layer and the insulating layer is insufficient in the '236 publication. This may result in foreign matter such as water and dust entering the accommodation chamber from between the conductive layer and the insulating layer.